COLUMBIA, SC (AP) – Mocking his critics, Donald Trump pledged Thursday to fully accept the outcome of next month’s presidential election — if he wins. The Republican said he reserved the right to contest questionable results, deepening his unsubstantiated assertions that the race against Hillary Clinton could be rigged against him.

Trump’s comments came a day after his stunning refusal in the final presidential debate to say whether he would concede to Clinton if he loses. His resistance, threatening to undermine the essence of American democracy, was roundly rejected by fellow Republicans.

With the presidential race slipping away from him, Trump has repeatedly raised the specter of a rigged election, despite no evidence of widespread voter fraud heading toward Election Day or in previous presidential contests. His top advisers and running mate Mike Pence have tried to soften his comments, only to watch helplessly as he plunges ahead.

Asked in Wednesday’s debate if he would accept the election results and concede to Clinton if he loses, Trump said: “I will tell you at the time. I will keep you in suspense.”

“The things that Donald Trump is saying and doing is genuinely a threat to the democratic process, which is based on trust,” Vice President Joe Biden said during a campaign stop for Clinton in New Hampshire.

Campaigning Thursday in must-win Ohio, Trump tried to make light of the situation.

“I would like to promise and pledge to all of my voters and supporters and to all of the people of the United States that I will totally accept the results of this great and historic presidential election,” he said. After letting that vow hang in the air for a few seconds, he added, “If I win.”

The Republican nominee said he would accept “a clear election result” but reserved his right to “contest or file a legal challenge” if he loses. He brushed off the likelihood of that happening with a confident prediction that “we’re not going to lose.”

SC Gov. Nikki Haley issued the following statement about Trump’s comments about a “rigged” election:

“This election is not rigged, and it’s irresponsible to say that it is. Faith in the democratic process is one of America’s greatest strengths, and it’s more important than the outcome of any election.”